How to init array in objective-c?

Question

I want to use an array in all methods of my class. The array is initialized in the init method of the class.

But the size of the array is first known in the init method. E.g. in my init method I have:

CGPoint mVertices[size][size];

later in init I fill the array and in another method I read the values. How can I declare the array globally?

user142019 · Accepted Answer · 2011-06-04 21:17:35Z

3

Make it an ivar:

@interface myClass : NSObject {
  CGPoint *mVertices;
}

@end

In your init method:

mVertices = malloc(size * size * sizeof(CGPoint));
if (!mVertices) { return nil; }

In your dealloc method:

free(mVertices); mVertices = NULL;

answered Jun 4, 2011 at 21:17

user142019

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2 Comments

just out of curiosity. Would you access this with mVertices[i][j] or with mVertices[i*size+j]?

Both are possible, but the [][] would most likely require multiple allocations.